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Novel compounds based on the 1,2,4-triazole skeleton were synthesized. A class of 4-amino-5-alkyl-4H-1,2,4-triazole-3- thione created by reaction of thiocarbohydrazide with long-chain aliphatic carboxylic acids, and then the Schiff bases were obtained in the media of heat and microwave waves, in the presence and the absence of a catalyst. Their chemical structures were assayed by elemental analysis, also device spectroscopic methods.
Turkish Journal of Chemistry Turk J Chem (2021) 45: 1805-1813 © TÜBİTAK doi:10.3906/kim-2105-39 http://journals.tubitak.gov.tr/chem/ Research Article Microwave irradiated synthesis of Schiff bases of 4-(arylideneamino)-5-alkyl-2,4dihydro-1,2,4-triazole-3-thione containing 1,2,4-triazole segment 2, Mahdi SHIRMOHAMMADI , Saeid SOUZANGARZADEH *, Dadkhoda GHAZANFARI , Mohsen GHODRATBEIGI , Mohammad Reza AKHGAR Department of Chemistry, Kerman branch, Islamic Azad University, Kerman, Iran Department of Chemistry, Faculty of Basic Science, Yadegare Imam Khomeini (RAH) Shahr-e Rey Branch, Islamic Azad University, Tehran, Iran Received: 17.05.2021 Accepted/Published Online: 18.07.2021 Final Version: 20.12.2021 Abstract: Novel compounds based on the 1,2,4-triazole skeleton were synthesized A class of 4-amino-5-alkyl-4H-1,2,4-triazole-3thione created by reaction of thiocarbohydrazide with long-chain aliphatic carboxylic acids, and then the Schiff bases were obtained in the media of heat and microwave waves, in the presence and the absence of a catalyst Their chemical structures were assayed by elemental analysis, also device spectroscopic methods Key words: 4-Amino-5-alkyl-4H-1,2,4-triazole-3-thione, thiocarbohydrazide, long-chain aliphatic carboxylic acids, Schiff bases Introduction Over the past decades, heterocyclic compounds and their various derivatives have attracted chemists due to their diverse applications in chemical and pharmaceutical fields Review references indicate that triazole compounds are of particular importance to other heterocyclic compounds due to their biological properties 1,2,4-triazoles exhibit a variety of biological properties, such as antimicrobial [1–5], antiinflammatory [6–8], anticonvulsant [9,10], anticancer [11,12,14,15], antitubercular [13], antibacterial [1,7,16-19], antifungal [1,20–22], antitubulin [23], insecticides [24], herbicidal [25] and anticorrosion [26] activities Due to potential properties of triazoles and the fact that one of the tasks of our research team is to investigate industrial emulsifiers, we expect such compounds to have emulsifying properties because they have a polar head and a long nonpolar tail So, we decided to make compounds that have such characteristics in addition to being new We succeeded to synthesize the structures of 4a-f and 5a-l using thiocarbohydrazide Materials and methods Solvents and analytical chemicals used were of analytical grade or dry distilled The qualitative analysis of compounds was evaluated by TLC, and the Rf values were assessed using prefabricated aluminum-silicon plates and Kieselgel 60 F254 (obtained from Merck) by using ethyl acetate as a molecule and the TLC which then visualized by means of a UV lamp Determining melting points was performed using Electrothermal melting furnace (B1 4300 BAMSETEP B1) Bruker Tensor 27 FT-IR spectrophotometer was used to record IR spectra Recording the NMR spectrum was handled in a Bruker Avance DRX-300 spectrometer with TMS as standard Mass spectra recorded on Finnigan-Matt 5973 Elemental analysis for C, H, N, and S determined using a Heracus CHN-O-Rapid analyzer Microwave irradiations were carried in a MicroSynth, Milestone microwave oven with 2500 W power 2.1 Synthesis of 4-Amino-5-alkyl-2,4-dihydro-[1,2,4]triazole-3-thione ( 4a-f ) A mixture consisting of carboxylic acid (0.01 mol) and thiocarbohydrazide (0.015 mol) was made in a round-bottomed flask heated on a mantle until content melted The resulting mixture was washed several times with warm water to remove unreacted thiocarbohydrazide and carboxylic acid and then collected by filtration To produce prementioned compounds, the product was recrystallized using ethanol * Correspondence: suzangarzade@iausr.ac.ir This work is licensed under a Creative Commons Attribution 4.0 International License 1805 SHIRMOHAMMADI et al / Turk J Chem 2.1.1 4-amino-5-heptyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4a) Yield 80%; white solid; m.p 115–117 ºC; IR υ (cm–1): 3320, 3200, 3152 (NH strength vibration of NH and NH2 groups), 2949-2851 (strength vibration of SP3 CH), 1486 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.84 (t, 3H, CH3), 1.23-1.26 (m, 8H, CH2), 1.56-1.63 (m, 2H, CH2), 2.59 (t, 2H, CH2), 5.49 (s, 2H, NH2), 13.40 (s, 1H, NH) Anal Calcd for C9H18N4S: C 50.44, H 8.47, N 26.14, S 14.95 found C 50.41, H 8.49, N 26.04, S 15.06 2.1.2 4-amino-5-nonyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4b) Yield 79%; white solid; m.p 114–115 ºC; IR υ (cm–1): 3320, 3200, 3152 (NH strength vibration of NH and NH2 groups), 2941-2851 (strength vibration of SP3 CH), 1486 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.84 (t, 3H, CH3), 1.23-1.25 (m, 12H, CH2), 1.58–1.64 (m, 2H, CH2), 2.59 (t, 2H, CH2), 5.50 (s, 2H, NH2), 13.40 (s, 1H, NH) Anal Calcd for C11H22N4S: C 54.51, H 9.15, N 23.12, S 13.22 found C 54.50, H 9.11, N 23.16, S 13.23 2.1.3 4-amino-5-undecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4c) Yield 78%; white solid; m.p 112–113.5 ºC; IR υ (cm–1): 3320, 3248, 3138 (NH strength vibration of NH and NH2 groups), 2933-2851 (strength vibration of SP3 CH), 1486 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.83 (t, 3H, CH3), 1.23-1.26 (m, 16H, CH2), 1.58–1.63 (m, 2H, CH2), 2.59 (t, 2H, CH2), 5.49 (s, 2H, NH2), 13.40 (s, 1H, NH) Anal Calcd for C13H26N4S: C 57.74, H 9.69, N 20.72, S 11.85 found C 57.80, H 9.65, N 20.75, S 11.80 2.1.4 4-amino-5-tridecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4d) Yield 75%; white solid; m.p 110–112.5 ºC; IR υ (cm-1): 3320, 3252, 3142 (NH strength vibration of NH and NH2 groups), 2927-2851 (strength vibration of SP3 CH), 1486 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.84 (t, 3H, CH3), 1.22-1.26 (m, 20H, CH2), 1.58–1.60 (m, 2H, CH2), 2.59 (t, 2H, CH2), 5.49 (s, 2H, NH2), 13.40 (s, 1H, NH) Anal Calcd for C15H30N4S: C 60.36, H 10.13, N 18.77, S 10.74 found C 60.26, H 10.20, N 18.80, S 10.74 2.1.5 4-amino-5-pentadecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4e) Yield 71%; white solid; m.p 108–110 ºC; IR υ (cm–1): 3320, 3153, 3043 (NH strength vibration of NH and NH2 groups), 2920-2851 (strength vibration of SP3 CH), 1486 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.83 (t, 3H, CH3), 1.22-1.26 (m, 24H, CH2), 1.58–1.60 (m, 2H, CH2), 2.59 (t, 2H, CH2), 5.48 (s, 2H, NH2), 13.40 (s, 1H, NH) Anal Calcd for C17H34N4S: C 62.53, H 10.50, N 17.16, S 9.82 found C 62.49, H 10.41, N 17.18, S 9.92 2.1.6 4-amino-5-heptadecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4f) Yield 70%; white solid; m.p 106–108 ºC; IR υ (cm-1): 3282, 3200, 3138 (NH strength vibration of NH and NH2 groups), 2922-2850 (strength vibration of SP3 CH), 1488 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.83 (t, 3H, CH3), 1.21-1.25 (m, 28H, CH2), 1.55–1.62 (m, 2H, CH2), 2.58 (t, 2H, CH2), 5.48 (s, 2H, NH2), 13.39 (s, 1H, NH) Anal Calcd for C19H38N4S: C 64.36, H 10.80, N 15.80, S 9.04 found C 64.25, H 10.70, N 15.90, S 9.15 2.2 Synthesis of 4-(arylideneamino)-5-substituted-2,4-dihydro-1,2,4-triazole-3-thione (5a-l) 2.2.1 Conventional procedure An equimolar amount of corresponding substituted benzaldehyde with to drops of glacial acetic acid was added to a suspension of substituted amino triazole (1.2 mol) in methanol The reaction mixture vessel was refluxed at temperature of 80–90°C for duration of to hours Obtained precipitate was then washed with water, subsequently filtered and finally dried 2.2.2 Microwave procedure Substituted amino triazole (1.2 mol) with an equimolar amount of the substituted benzaldehyde were mixed with 4–5 drops of DMSO and exposed to microwave irradiation at 80 °C (400 W) (see Table 1) using a Micro Synth lab station reactor The reaction was carried within high-pressure Teflon reactor equipped with a magnetic stir bar and an optical fiber (to control resulting temperature) Then, the mixture vessel was allowed to cool down while adding 20 mL water, and the obtained material was then filtered and washed using 10 mL of hot water and finally recrystallized in methanol 2.2.3 4-(benzylideneamino)-5-heptyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5a) Yield(%): 93(60); white solid; m.p 119–121 ºC; IR υ (cm–1): 3114 (NH strength vibration of NH group), 2950-2850 (strength vibration of SP3 CH), 1581, 1500 (strength vibration of C = C aromatic), 1469 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.82 (t, 3H, CH3), 1.26–1.42 (m, 8H, CH2), 1.74–1.80 (m, 2H, CH2), 2.84 (t, 2H, CH2), 7.46-7.87 (m, 5H, Ar), 10.35 (s, 1H, HC = N), 13.40 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ 14.2-31.8 (aliphatic, carbons), 128.6133.4 (aromatic, carbons) 153.9, 157.2 (imine groups, carbons), 181.3 (thione group, carbon); M.S, m/z 302 (M+, 5%), 287 (M-NH, 3%), 258 (M-CS, 10%), 243 (M-NH-CS, 12%) Anal Calcd for C16H22N4S: C 63.54, H 7.33, N 18.53, S 10.60 found C 63.60, H 7.30, N 18.55, S 10.55 1806 SHIRMOHAMMADI et al / Turk J Chem Table Chemical structures of 1,2,4-triazole 4a-f and Schiff base 5a-l Entry Compounds R1 R2 4a n-C7H15 4b 4c Yield (%) Conventional heating Microwave heating (12 min.) - 80 - n-C9H19 - 79 - n-C11H23 - 78 - 4d n-C13H27 - 75 - 4e n-C15H31 - 71 - 4f n-C17H35 - 70 - 5a n-C7H15 H 60 93 5b n-C9H19 H 60 93 5c n-C11H23 H 59 92 10 5d n-C13H27 H 58 92 11 5e n-C15H31 H 57 91 12 5f n-C17H35 H 57 90 13 5g n-C7H15 OH 62 94 14 5h n-C9H19 OH 61 93 15 5i n-C11H23 OH 61 93 16 5j n-C13H27 OH 59 92 17 5k n-C15H31 OH 59 91 18 5l n-C17H35 OH 58 91 2.2.4 4-(benzylideneamino)-5-nonyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5b) Yield(%): 93(60); white solid; m.p 116–118 ºC; IR υ (cm–1): 3114 (strength vibration of NH group), 2950-2850 (strength vibration of SP3 CH), 1581, 1500 (strength vibration of C = C aromatic), 1468 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.82 (t, 3H, CH3), 1.21–1.40 (m, 12H, CH2), 1.70-1.89 (m, 2H, CH2), 2.80 (t, 2H, CH2), 7.46-7.87 (m, 5H, Ar), 10.31 (s, 1H, HC=N), 13.40 (s, 1H, NH ); 13C NMR (75 MHz DMSO-d6) δ14.4-34.10 (aliphatic, carbons), 128.6–133.4 (aromatic, carbons), 153.9, 157.2 (imine, carbons), 181.3 (thione, carbon); M.S, m/z 330 (M+, 6%), 315 (M-NH, 4%), 286 (N-C-S, 11%), 271 (M-NH-CS, 13%) Anal Calcd for C18H26N4S: C 65.42, H 7.93, N 16.95, S 9.70 found C 65.55, H 7.86, N 16.84, S 9.75 2.2.5 4-(benzylideneamino)-5-undecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5c) Yield(%): 92(59); white solid; m.p 112–115 ºC; IR υ (cm–1): 3112 (strength vibration of NH group), 2950-2850 (strength vibration of SP3 CH), 1581, 1500 (strength vibration of C = C aromatic), 1468 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.80 (t, 3H, CH3), 1.24–1.41 (m, 16H, CH2), 1.67–1.83 (m, 2H, CH2), 2.78 (t, 2H, CH2), 7.46–7.87 (m, 5H, Ar), 10.28 (s, 1H, HC = N), 13.39 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6)δ14.3-34.0 (aliphatic, 11 carbons), 128.8–133.2 (aromatic, carbons), 154.9, 157.1 (imine, carbons), 181.6 (thione, carbon); M.S, m/z 358 (M+, 4%), 343 (M-NH, 4%), 314 (N-C-S, 11%), 299 (M-NH-CS, 12%) Anal Calcd for C20H30N4S: C 67.00, H 8.43, N 15.63, S 8.94 found C 66.91, H 8.50, N 15.60, S 8.99 2.2.6 4-(benzylideneamino)-5-tridecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5d) Yield(%): 92(58); white solid; m.p 99–111.5 ºC; IR υ (cm–1): 3112 (strength vibration of NH group), 2950-2850 (strength vibration of SP3 CH), 1581, 1500 (strength vibration of C = C aromatic), 1468 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.80 (t, 3H, CH3), 1.16–1.38 (m, 20H, CH2), 1.60-1.62 (m, 2H, CH2), 2.73 (t, 2H, CH2), 7.47–7.86 (m, 5H, Ar), 10.23 (s, 1H, HC=N), 13.40 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6)δ14.1-35.1 (aliphatic, 13 carbons), 127.9–133.1 (aromatic, carbons), 154.1, 158.1 (imine, carbons), 181.2 (thione, carbon); M.S, m/z 386 (M+, 5%), 371 (M-NH, 4%), 342 (N-C-S, 12%), 327 (M-NH-CS, 11%) Anal Calcd for C22H34N4S: C 68.36, H 8.86, N 14.49, S 8.29 found C 68.33, H 8.85, N 14.47, S 8.35 1807 SHIRMOHAMMADI et al / Turk J Chem 2.2.7 4-(benzylideneamino)-5-pentadecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5e) Yield(%): 91(57); white solid; m.p 96–98 ºC; IR υ (cm–1): 3112 (NH strength vibration of NH group), 2950-2850 (strength vibration of SP3 CH), 1581, 1500 (strength vibration of C=C aromatic), 1468 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.80 (t, 3H, CH3), 1.15–1.23 (m, 24H, CH2), 1.57–1.64 (m, 2H, CH2), 2.68 (t, 2H, CH2), 7.47–7.86 (m, 5H, Ar), 10.23 (s, 1H, HC=N), 13.41 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6)δ14.1-29.7 (aliphatic, 15 carbons), 127.9133.1 (aromatic, carbons), 154.1, 158.1 (imine, carbons), 181.2 (thione, carbon); M.S, m/z 414 (M+, 6%), 399 (M-NH, 6%), 370 (N-C-S, 13%), 355 (M-NH-CS, 14%) Anal Calcd for C24H38N4S: C 69.52, H 9.24, N 13.51, S 7.73 found C 69.38, H 9.17, N 13.63, S 7.82 2.2.8 4-(benzylideneamino)-5-heptadecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5f) Yield(%): 90(57); white solid; m.p 90–92 ºC; IR υ (cm–1): 3115 (NH strength vibration of NH group), 2921-2851 (strength vibration of SP3 CH), 1583, 1499 (strength vibration of C=C aromatic), 1417 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.81 (t, 3H, CH3), 1.08–1.26 (m, 28H, CH2), 1.60–1.71 (m, 2H, CH2), 2.69 (t, 2H, CH2), 7.52-7.88 (m, 5H, Ar), 10.23 (s, 1H, HC = N), 13.40 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ13.9-34.2 (aliphatic, 17 carbons), 128.7132.9 (aromatic, carbons), 153.7, 157.2 (imine, carbons), 182.1 (thione, carbon); M.S, m/z 442 (M+, 7%), 427 (M-NH, 5%), 398 (N-C-S, 9%), 383 (M-NH-CS, 13%) Anal Calcd for C26H42N4S: C 70.54, H 9.56, N 12.66, S 7.24 found C 70.61, H 9.51 N 12.61, S 7.27 2.2.9 5-heptyl-4-((2-hydroxybenzylidene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (5g) Yield(%): 94(62); white solid; m.p 125–127 ºC; IR υ (cm–1): 3450-3200 (strength vibration of OH group), 3105 (strength vibration of NH group), 2917-2850 (strength vibration of SP3 CH), 1585, 1488 (strength vibration of C=C aromatic), 1465 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.82 (t, 3H, CH3), 1.26–1.42 (m, 8H, CH2), 1.56–1.71 (m, 2H, CH2), 2.73 (t, 2H, CH2), 6.80–7.33 (m, 4H, Ar), 10.32 (s, 1H, HC=N), 10.89 (s, 1H, OH), 13.40 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ13.8-31.9 (aliphatic, carbons), 117.7–132.3, 156.7 (aromatic, carbons), 143.4, 156.0 (imine, carbons), 181.2 (thione, carbon); M.S, m/z 318 (M+, 6%), 303 (M-NH, 5%), 274 (N-C-S, 10%), 259 (M-NH-CS, 11%) Anal Calcd for C16H22N4OS: C 60.35, H 6.96, N 17.59, O 5.03, S 10.07 found C 60.50, H 6.99, N 17.51, O 4.99 S 10.0.1 2.2.10 4-((2-hydroxybenzylidene)amino)-5-nonyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5h) Yield(%): 93(61); white solid; m.p 121–124 ºC; IR υ (cm–1): 3430-3190 (strength vibration of OH group), 3150 (strength vibration of NH group), 2930-2860 (strength vibration of SP3 CH), 1590, 1495 (strength vibration of C = C aromatic), 1475 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.83 (t, 3H, CH3), 1.20–1.25 (m, 12H, CH2), 1.60–1.65 (m, 2H, CH2), 2.65 (t, 2H, CH2), 6.83-7.45 (m, 4H, Ar), 10.51 (s, 1H, HC = N), 10.89 (s, 1H, OH), 13.40 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ14.3-34.2 (aliphatic, carbons), 117.5–132.1, 157.2 (aromatic, carbons), 143.1, 156.3 (imine, carbons), 181.5 (thione, carbon); M.S, m/z 346 (M+, 5%), 331 (M-NH, 4%), 302 (N-C-S, 12%), 287 (M-NH-CS, 14%) Anal Calcd for C18H26N4OS: C 62.40, H 7.56, N 16.17, O 4.62, S 9.25 found C 62.30, H 7.53, N 16.21, O 4.66, S 9.30 2.2.11 4-((2-hydroxybenzylidene)amino)-5-undecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5i) Yield(%): 93(61); white solid; m.p 116-118 ºC; IR υ (cm–1): 3500-3250 (strength vibration of OH group), 3180 (strength vibration of NH group), 2950-2840 (strength vibration of SP3 CH), 1595, 1500 (strength vibration of C=C aromatic), 1470 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.82 (t, 3H, CH3), 1.26–1.42 (m, 16H, CH2), 1.47–1.80 (m, 2H, CH2), 2.49 (t, 2H, CH2), 6.79–7.45 (m, 4H, Ar), 10.50 (s, 1H, HC = N), 10.89 (s, 1H, OH), 13.41 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ14.4-34.1 (aliphatic, 11 carbons), 117.5-133.1, 157.4 (aromatic, carbons), 144.8, 156.9 (imine, carbons), 181.4 (thione, carbon); M.S, m/z 374 (M+, 5%), 359 (M-NH, 5%), 330 (N-C-S, 12%), 315 (M-NH-CS, 11%) Anal Calcd for C20H30N4OS: C 64.14, H 8.07, N 14.96, O 4.27, S 8.56 found C 64.25, H 8.05, N 14.86, O 4.31, S 8.53 2.2.12 4-((2-hydroxybenzylidene)amino)-5-tridecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5j) Yield(%): 92(59); white solid; m.p 112-115 ºC; IR υ (cm–1): 3480-3210 (strength vibration of OH group) ), 3145 (strength vibration of NH group), 2945-2833 (strength vibration of SP3 CH), 1600, 1490 (strength vibration of C = C aromatic), 1466 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.81 (t, 3H, CH3), 1.06–1.18 (m, 20H, CH2), 1.56–1.63 (m, 2H, CH2), 2.67 (t, 2H, CH2), 6.82-7.44 (m, 4H, Ar), 10.49 (s, 1H, HC = N), 10.89 (s, 1H, OH), 13.39 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ14.5-34.9 (aliphatic, 13 carbons), 117.3–131.9, 157.7 (aromatic, carbons), 143.6, 157.1 (imine, carbons), 181.3 (thione, carbon); M.S, m/z 402 (M+, 6%), 387 (M-NH, 4%), 358 (N-C-S, 12%), 343 (M-NH-CS, 12%) Anal Calcd for C22H34N4OS: C 65.63, H 8.51, N 13.92, O 3.97 S 7.97 found C 65.75, H 8.47, N 13.85, O 3.95, S 7.98 2.2.13 4-((2-hydroxybenzylidene)amino)-5-pentadecyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (5k) Yield(%): 91(59); white solid; m.p 108–110 ºC; IR υ (cm–1): 3500-3200 (strength vibration of OH group) ), 3105 (strength vibration of NH group), 2917-2850 (strength vibration of SP3 CH), 1597, 1509 (strength vibration of C = C aromatic), 1467 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.81 (t, 3H, CH3), 1.26-1.32 (m, 24H, CH2), 1.74–1.80 (m, 1808 SHIRMOHAMMADI et al / Turk J Chem S H2N O N H + NH2 N H R1 Fusion TCH OH S HN N NH2 N R1 NH2NH2 O H N R1 - S K + N H S CS 2, K O H O R1 N H NH2 O 1) CH3CH2OH, H 2) NH2NH2 R1 OH Figure Synthesis of 1,2,4-triazole amines 4a-f 2H, CH2), 2.65 (t, 2H, CH2), 6.80–7.46 (m, 4H, Ar), 10.43 (s, 1H, HC=N), 10.84 (s, 1H, OH), 13.40 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ14.6-34.0 (aliphatic, 15 carbons), 117.8–132.3, 157.8 (aromatic, carbons), 143.3, 157.1 (imine, carbons), 182.1 (thione, carbon); M.S, m/z 430 (M+, 7%), 415 (M-NH, 3%), 386 (N-C-S, 11%), 371 (M-NH-CS, 14%) Anal Calcd for C24H38N4OS: C 66.94, H 8.89, N 13.01, O 3.72 S 7.44 found C 67.01, H 8.94, N 12.96, O 3.69, S 7.40 1809 SHIRMOHAMMADI et al / Turk J Chem 2.2.14 5-heptadecyl-4-((2-hydroxybenzylidene)amino)-2,4-dihydro-3H-1,2,4-triazole-3-thione (5l) Yield(%): 91(58); white solid; m.p 97–99 ºC; IR υ (cm–1): 3480-3330 (strength vibration of OH group) ), 3105 (strength vibration of NH group), 2918-2840 (strength vibration of SP3 CH), 1593, 1505 (strength vibration of C = C aromatic), 1466 (bending vibration of CH2); 1H NMR (300 MHz DMSO-d6) δ 0.80 (t, 3H, CH3), 1.16–1.22 (m, 28H, CH2), 1.57–1.64 (m, 2H, CH2), 2.68 (t, 2H, CH2), 6.85–7.46 (m, 4H, Ar), 10.44 (s, 1H, HC = N), 10.88 (s, 1H, OH), 13.41 (s, 1H, NH); 13C NMR (75 MHz DMSO-d6) δ14.9-34.2 (aliphatic, 17 carbons), 118.1–131.9, 157.1 (aromatic, carbons), 143.4, 156.9 (imine, carbons), 182.4 (thione, carbon); M.S, m/z 458 (M+, 6%), 443 (M-NH, 5%), 414 (N-C-S, 11%), 399 (M-NH-CS, 11%) Anal Calcd for C26H42N4OS: C 68.08, H 9.22, N 12.21, O 3.50, S 6.99 found C 68.07, H 9.25, N 12.18, O 3.52, S 6.98 Results and discussion In a continuous research works of this group [27–34], 18 triazole amines and Schiff bases were synthesized The difference among these compounds is in the R1 acid group and the R2 aldehyde group Our research team performed the reaction of thiocarbohydrazide (TCH) with long-chain aliphatic carboxylic acids (1a-f) in different conditions and analyzed the reaction of the resulting products with benzaldehyde and its derivatives under various conditions The reaction of TCH with octanoic acid 1a in the fusion method yielded product 4a (Figure 1), and it was confirmed as 4-amino-5-heptyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (4a) The structure of 4a was assessed and approved as compared to its spectral data (1H NMR, IR) Also, triazole 4a was synthesized in three steps reaction as well Hydrazide (2) was obtained by the ethanolysis and then hydrazinolysis of carboxylic acid (1) The required dithiocarbazinate (3) was synthesized by reacting hydrazide with carbon disulfide and ethanolic solution of potassium hydroxide And 1,2,4-triazole(4) was produced by the reaction of intramolecular cyclization from the yielded salt with hydrazine The advantage of the first method is the lower steps and higher efficiency The triazole synthesized in this way was then condensed with benzaldehyde As a catalyst, the reaction was performed in the presence of concentrated sulfuric acid or glacial acetic acid (few drops) to yield Schiff base (Figure 2) The Schiff base formation reaction was carried out by the use of bronsted acid The reaction was also accomplished in the presence of heterogeneous inorganic solid acidic catalysts such as beta-zeolite and montmorillonite-KSF under heat conditions And also, the reaction was conducted in the absence of catalyst in microwave environment The efficiency obtained using zeolite and montmorillonite was approximately similar Besides, when the reaction was carried out under microwave conditions, the reaction time was reduced and the efficiency increased The obtained yield using catalyst and in conventional method was moderate Reactions were evaluated at different times The best results were obtained with acetic acid in the thermal method for 90 and in the microwave method for 12 (see Table 2) S HN N NH2 EtOH + N O R2 R1 4a-f R1 N N NH N S R2 5a-l Figure Synthesis of Schiff base 5a-l 1810 glacial acetic acid or zeolite or montmorillonite or microwave irradiation SHIRMOHAMMADI et al / Turk J Chem Table The effect of catalyst on the reaction efficiency of Schiff base 5a* Yield (%) Time (min.) Conventional heating Microwave heating Acetic acid β-Zeolite Montmorillonite KSF - - - 90 - - - 91 10 - - - 92 12 - - - 93 30 53 51 54 - 45 55 51 55 - 60 56 52 56 - 90 60 52 57 - * The effect of the catalyst was investigated only on 5a The reaction efficiency using microwaves did not change significantly with increasing time The start of the reaction in the presence of the catalyst was after 30 The path for synthesizing proposed compounds 4a-f and 5a-l is outlined in Figures and 4a-f was approved by IR and 1H NMR spectroscopic methods 5a-f was also fully characterized using various spectroscopic methods The progress for reactions was assessed using TLC (thin layer chromatography) Elemental analysis was used to check the purity of all compounds The position of IR bands suggests enough evidence regarding the formation of 4a and 5a The bands due to υ ( C = N ) and υ (C = S) stretch at 1616 cm–1 and 1223 cm–1, which approves the formation of triazole 4a The absence of υ (NH2) band in the IR spectrum of 4a shows the formation of 5a Other signs for the formation of 4a and 5a were attained by 1H NMR and 13C NMR spectroscopies In the 1H NMR of triazole 4a in d6-DMSO, signals for the NH proton of triazole ring and for the NH2 protons were observed at 13.40 ppm and 5.49 ppm, respectively In the 1H NMR of Schiff base 5a in d6-DMSO, signal for the CH proton of imine bond was observed at 10.35 ppm, beside the 13C NMR spectrum signal at 154.1 or 157.0 ppm due to -CH=N- carbon atom Also, in the mass spectrum of 5a, fragment 302 obtained These results support for the proposed structures of 4a and 5a Conclusion In this work, Schiff base was prepared in two steps In the first stage, amine triazole was prepared from the reaction of thiocarbohydrazide and carboxylic acid, and in the second stage, compound reacted with benzaldehyde and its derivatives and the final product was obtained.The second step reaction was performed using sulfuric or acetic acid, zeolite, montmorillonite, and microwave irradiations The best efficiency was achieved in the microwave References Behalo MS, Gad El-karim IA, Issac YA, Farag MA Synthesis of novel pyridazine derivatives as potential antimicrobial agents Journal of Sulfur Chemistry 2014; 35 (3): 661-673 doi: 10.1080/17415993.2014.950661 Mishra R, Kumar R, Kumar S, Majeed J, Rashid M et al Synthesis and in vitro antimicrobial activity of some triazole derivatives Journal of the Chilean Chemical Society 2010; 55 (3): 359-362 doi: 10.4067/S0717-97072010000300019 Karabasanagouda T, Adhikari AV, Shetty NS Synthesis and antimicrobial activities of some novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines carrying thioalkyl and sulphonyl phenoxy moieties European Journal of Medicinal Chemistry 2007; 42 (4): 521-529. doi: 10.1016/j.ejmech.2006.10.010 Patil BS, Krishnamurthy G, Shashikumar ND, Lokesh MR, Naik HSB. 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Biernasiuk A, Paruch K, Paruch K, Patrejko P, Wujec M Synthesis and evaluation of antimicrobial properties of new Mannich bases of 4,5-disubstituted -1,2,4-triazole- 3-thiones Phosphorus, Sulfur, and... al Synthesis of essramycin and comparison of its antibacterial activity Journal of Natural Products 2010; 73 (11): 1940–1942 doi: 10.1021/np100648q 19 Yang J, Zhao Z, Li H Synthesis using microwave. .. cm–1, which approves the formation of triazole 4a The absence of υ (NH2) band in the IR spectrum of 4a shows the formation of 5a Other signs for the formation of 4a and 5a were attained by 1H NMR